The present invention is directed to a probe used for a scanning probe microscope (hereinafter, referred to as SPM) and a method of fabricating the probe. More particularly, the present invention is directed to a probe for an SPM and a method of fabricating the probe in which a double side alignment process is not required to simplify the fabricating.
The SPM is a microscope capable of observing various shapes on a surface of an object by nano meters that cannot be observed by an optical or electron microscope, and is used widely, now. In recent years, methods for realizing a highly integrated storage device using the SPM have been studied and much used in a photolithography for forming fine patterns. In the SPM, a probe is used to scan a surface of an object.
A general structure of a probe is shown in FIG. 1. FIG. 1 is a photograph of a probe taken by a scanning electron microscope (SEM). The probe includes a cantilever 101, a body 102 supporting the cantilever 101 and a tip 103 formed at the end of the cantilever 101. The cantilever 101 includes two legs of which one ends are connected to a side of the body 102 and of which the other ends are connected to each other, so that the two legs form a triangle. A position where the other ends of the two legs are connected to each other is formed with the tip 103.
The conventional probe is made of silicon dioxide, silicon nitride, metal, silicon and the like. Specifically, silicon is widely used as probe material because of its excellent mechanical characteristic. When the silicon is used as probe material, silicon on insulator (SOI) wafer is usually as a silicon substrate.
An example of fabricating a probe of a AFM (Atomic Force Microscope) using the SOI wafer is described in a paper published with IEEE in 1991 by C. F. Quate et al., entitled “Atomic Force Microscope Using a Piezoresistive Cantilever”. According to this paper, a silicon cantilever is fabricated through a double side alignment process, using a silicon dioxide at the center of the SOI wafer as an etching-stopper layer. In this case, the cantilever is made of silicon with an excellent mechanical characteristic to obtain a sharp tip. However, because a complicate double side alignment process is used and a position of the silicon dioxide where etching is stopped is varied according to a thickness of the SOI wafer, a length of the cantilever is not constant. Also, because the SOI wafer is expensive, cost in mass production thereof increases.
An example of fabricating a probe of a AFM (Atomic Force Microscope) using silicon dioxide, silicon nitride, metal and the like except for the silicon is described in U.S. Pat. No. 4,968,585, patented to T. R. Albrecht et. al, on Nov. 6th in 1990 and U.S. Pat. No. 5,021,364, patented to C. F. Quate et. al, on Jun. 4th in 1991. In these patents in which the probe of a AFM is made of silicon dioxide, silicon nitride, metal and the like, the mechanical characteristic of the cantilever is not as good as that of the silicon cantilever and a range in which a thickness of the cantilever can be adjusted is limited. In addition, deposition characteristic of deposited films make the tip not as sharp as the silicon tip.
Therefore, a probe for an SPM and a method of fabricating the probe in which a probe with an excellent performance can be fabricated in simpler processes and in lower cost have been required.